Electrical machine rotor



Oct. 11, 1960 E. J. Buss ETAL ELECTRICAL MACHINE Ro'roR Filed Oct. 23,1957 United States Patent @ffice 2,956,189 Patented Oct. 11, 1960ELEC'I'RICAL MACHINE ROTOR Edward J. Buss, Guy Russell Fansher, John H.Groves, and George E. ODonald, all of Freeport, Ill., assignors toFairbanks, Morse & Co., Chicago, Ill., a corporation of Illinois FiledOct. 23, 1957, Ser. No. 691,939

5 Claims. (Cl. 310-211) This invention relates to improvements in rotorsfor electrical machines, and more particularly to an improved rotorconstruction for an electrical machine of the socalled axial air gaptype.

An object of the present invention is to provide a unitary rotorcomprised of a rotor frame, a magnetic core and a cast squirrel-cagetype winding, wherein the rotor is characterized by an improvedconstruction affording rigid assembly connection of the parts by thecast winding.

Another object is to provide a unitary rotor of the character indicated,wherein the rotor frame embodies means locating the core on the frameand serving in Acooperation with the cast Winding, to effect securementof the core and frame in rigid assembly.

A further object is to aiford a rotor construction of the aforesaidcharacter, which facilitates production of the cast winding bycentrifugal casting to the frame and core.

Other objects and advantages attained will appear from the followingdescription of a presently preferred embodiment of the invention, assuch is illustrated by the accompanying drawing, wherein:

Fig. 1 is a sectional view of the improved rotor as taken at one side ofits axis, and

Fig. 2 is a reduced, front elevation of the rotor with portions brokenaway to illustrate details thereof, the View being taken from line 2-2in Fig. 1.

Referring to the drawing, the presently improved rotor is of the axialair gap type and comprises, essentially, a rotor frame 10, a magneticcore member 11, and a cast winding 12 of squirrel-cage form. Rotor frame10 is a unitary member which is formed to provide a disc body 14 havinga Shaft-mounting hub structure generally indicated at 15. The hub 15includes an annular hub portion 16 projecting from one side of the body14 and an annular hub portion 18 projecting from the other side of thebody, the latter terminating in a shaft seating portion 19 receiving theend 20 of the rotor shaft 22 to which it is keyed or pinned, as by thepin 23, for rotation of the rotor and shaft as a unit. The hub portion16 presents an internal bore 24 providing access to a reduced linternalbore 26 formed partly in hub portion 16 and in hub portion 18, bore 26receiving an anti-friction type bearing unit indicated at 27, forrotatably supporting the rotor on a stationary part indicated at 28 inbroken lines of the stator (not shown) with which the rotor cooperates.

'I'he rotor frame body 14 provides an annular planar surface or face 30on the side thereof from which the hub portion 16 projects, such facebeing in a plane transversely of the rotor axis and normal thereto.Integral with the opposite side 31 of the body and the hub portion 18are a plurality of fan blades, one of which s shown at 32 in Fig. 1.Body surface 30 affords a mounting seat portion for the rotor coremember 11 which, in rotor assembly, has its back planar side 34 insurface abutment with the frame face 30. The core as shown, is anannular, laminated member of magnetic material, and preferablyconstructed of a single strip of sheet core iron punched to providewinding slots and wound in coil form. Construction of such a core may bein accordance with the teaching of Letters Patent 2,123,350 to G. R.Anderson. The core thus produced, has the back surface 34 heretoforenoted, a parallel planar air gap face 35, inner and outer circularperipheries 36 and 38 respectively, and Winding slots 39 each extendingto the gap face, as at 40 (Fig. 2) and open at the inner and outer coreperipherles.

Location of the core on the frame seat portion 30 such that it will bein spaced, concentric relation to the frame hub portion 16, on a centercoincident with the rotational axis of the frame, is attained by hubprojections or anges 42 (three being shown in the present embodiment,Fig. 2) engaging the inner periphery 36 of the core. The projections orflanges 42 are generally radially outstanding on the outer circularsurface 43 of hub portion 16, and are equally angularly spaced about thehub, as shown in Fig. 2, and spaced outwardly from the body surface 30as Shown by Fig. l. Each projection is elongate in the circulardirection of the hub, and provides a curved peripheral edge or face 44the curvature of which is on a radius having a center coincident withthe rotational center of the rotor frame, and opposite end margins 46which may be substantially radial or directed inwardly, as shown, at anacute angle to a radius. These projections or flanges 42 having thecurved edges 44 in Contact with the inner periphery 36 of the core, thusattain the desired centering of the core and serve in addition, as coremounting seat means in cooperation with the frame seat 30, and asassembly locking means in a manner presently to appear.

In order to facilitate formation of the present unitary rotor, it isimportant that the rotor frame as now described, be constructed toafford both positional and dimensional accuracy of its parts,particularly in regard to the planar mounting face 30 and thehub-carried projections 42. To such end, advantage is taken of the nowwell-known shell-molding process to produce the rotor frame as ashell-mold cast member of suitable material, such as iron or if desired,a non-magnetic metal. The resultant cast frame, presenting an improvedcasting characterized by uniform metal density and smooth, accuratelyformed surfaces, thus materially reduces the extent of any machiningwhich may be necessary, as at the body surface y30 and projection edges44, for accurate core seating.

Having the rotor frame and core member each formed as now described, thecore is positioned on the projections 42 and in abutment with frame bodysurface 30, and the assembled parts are then placed in a mold forcasting of the rotor winding 12 thereto. The winding, which may be ofcopper, aluminum or other suitable or desired conducting material, iscast preferably by centrifugal casting. For example, centrifugal castingthereof may be attained in accordance with the teachings of LettersPatent 2,304,067 to G. R. Anderson. The resulting cast winding providesan outer end ring 50 in cast connection to the outer periphery 33 of thecore and to the outer annular face portion 51 of frame face 30 exposedbeyond the core member; an inner end ring 52 in cast connection to theinner periphery 36 of the core, to the inner exposed portion 54 of frameface 30, and to the hub projections 42, the latter thus being embeddedin the cast winding end ring 52, and winding bars (such as bar 55 shownin Fig. l) filling the core slots 39 and integrally joining the endrings 50 and 52. The winding 12. as cast, thus effects a secure assemblyconnection of the rotor frame and core, wherein the projections 42embedded in cast end ring 52 effectively key or lock the casting, andhence the core 11, to the frame and its hub portion 16.

It will be appreciated now that the present improvements alford anelectrical machine rotor characterized by simplicity and greaterdimensional accuracy of construction, and by a unitary structure whereinthe frame and core members are rigidly retained in assembly by the castWinding, as in the manner described.

Having described and illustrated one preferred embodiment of theinvention, it is to be understood that various alterations andmodifications may be made therein without departing from the spirit andscope of the invention as hereinafter claimed.

What is claimed is:

1. A rotor for an electrical machine of axial air gap type, comprising arotor frame having a hub and providing a core-engaging surface, anannular magnetic core on said frame surface, flange means on said huband in engagement with the core solely at its inner periphery, 1ocatingthe core concentrically of the hub, and a Winding of conducting materialin cast assembly to the core, rotor frame and flange means, securing theframe and core in rigid assembly.

2. A rotor for an electrical machine of axial air gap type, comprising7a rotor frame having a hub and providing a core-engaging Surface, anannular slotted magnetic core on said frame surface, said core having acircular inner periphery, integral hub projections equally spaced aboutthe hub and spaced from said frame surface, said projections engagingthe said circular inner periphery of. the core and locating the coreconcentrically of the hub, and a winding of conducting material in castassembly to the slotted core, rotor frame and projections, securing thecore and frame in rigid assembly.

3. A rotor for an electrical machine of axial air gap type, comprising arotor frame having a hub providing a circular outer surface, said frameproviding a planar core-receiving surface normal to the axis of the hub,an annular core on said planar surface, said hub having integralelements projecting radially from said outer hub surface and spacedaxially from said planar surface, the elements engaging the core at itsinner periphery and locating the core concentrically of the hub, and aWinding of conducting material in cast assembly to the core, frame andelements, securing the frame and core in rigid assembly.

4. A rotor for an electrical machine of axial air gap type, comprising arotor frame providing a disc body and a central hub, said body having aplanar core-mounting face normal to the rotor axis, said hub including ashaftengaging portion and a hub portion projecting axially from theplanar face of said body, the hub further pro- Cil viding an axialbearing-receiving recess, a plurality of iiange elements radiallyoutstanding on said projecting hub portion and spaced from said planarface, an annular slotted core member of magnetic material, positioned inabutment with said planar body face and having its inner peripheryengaging said flange elements, said ilange elements disposing the coremember in a position concentric of said hub portion, and a cast windingproviding an outer end ring in cast connection toy the frame and theouter periphery of the core member, an inner end ring in cast connectionto the frame, the inner periphery of the core member and said flangeelements, and Winding bars in the slots of the core member and integralWith the end rings, said cast Winding thereby securing the frame andcore member in rigid assembly.

5. A rotor member for electrical machines of axial air gap type,comprising a unitary, shell-mold cast rotor frame providing a hub, adisc body having a planar face normal to the axis of the hub, the hubincluding a hub portion projecting from said planar face, and liangeelements radially outstanding on said hub portion and spaced from theplanar face, said rotor frame being characterized by smooth as-castsurfaces; an annular core of magnetic material, having planar front andback surfaces and slots open at the front surface and at the inner andouter peripheral surfaces of the core, said core being disposed on therotor frame with its back surface against said planar face and its innerperipheral surface in seating engagement with said flange elements, theflange elements seating the core concentrically of said hub portions;and a body of conducting material in centrifugally cast assembly to thecore and rotor frame, providing an outer end ring embracing the coreover its outer peripheral surface, an inner end ring in engagement withthe inner peripheral surface of the core and with said hub portion andflange elements, and bars in the core slots between said end rings, saidconducting material body as cast, securing the rotor frame and core inrigid assembly.

References Cited in the le of this patent UNITED STATES PATENTS1,934,981 `Johnson Nov. 14, 1933 2,245,577 Dieckman June 17, 19412,490,021 Aske Dec. 6, 1949 2,510,917 Turner et al. June 6, 19502,740,910 Fleischer Apr. 3, 1956 2,880,335 Dexter Mar. 3l, 1959Disclaimer 2,956,189.EZwwd J. Buss, Guy Russell Famke?, J 07m H. Gwwes,and Geom/e E. ODoowld, Freeport, Ill. 'ELECTRICAL MACHNE ROTOR. Patentelated Oct. 1l, 1960. Disclaimer filed Jan. 3, 1966, by the assignee,The I miie/rial E lef/Wie Compa/ny. v Hereby enters this disclaimer tothe remaining' term of said patent.

[Oycial Gazette May 24,1966] Disclaimer 2,956,189.-E6Zwm"d J. Buss, GuyRussell Fanshee", J 07m H. Gv'owes, and George E. ODmmld, Freeport, Iii.ELECTRICAL MACHNE ROTOR. Patent dated Oct. 11, 1960. Disclaimer iledJan. 3, 1966, by the asszignee, The I mpem'al Eleetw'e @empa/ny. Herebyenters this disclaimer to the remaining' term of said patent.

[Oez'l Gazette May 24, 1966.]

